1. Field of the Invention
This invention relates to a light source device and an optical apparatus, and particularly to a light source device forming a surface illuminant and an optical apparatus suitable when an object to be illuminated such as film or a liquid crystal panel is illuminated by a light beam from the surface illuminant.
2. Related Background Art
There have heretofore been proposed various light source devices in which a fluorescent lamp is provided parallel to a side of a transparent acrylic plate having its surface formed into a rough surface and rays of light from this fluorescent lamp are caused to enter the interior of the acrylic plate from the side and propagate through the interior and make the rough surface of the acrylic plate shine to thereby form a surface illuminant.
However, in the surface illuminant according to the conventional art, the luminance of the fluorescent lamp is higher at the center thereof than at the margin thereof and therefore, the luminance at the center is high and the luminance at the margin is low, and this has led to the problem that luminance irregularity occurs.
It is the object of the present invention to provide a light source device and an optical apparatus in which luminance distribution is controllable and accordingly this kind of luminance irregularity can be made small.
The light source device of the present invention is characterized by a group of light emitting elements and adjusting means for individually adjusting the luminance of each light emitting element in the group of light emitting elements and a transparent plate-like member in which a beam of light from the group of light emitting elements is caused to enter the interior of the plate-like member from a side of the plate-like member to thereby form a surface illuminant.
The invention has a form in which the light emitting elements are LEDs (light emitting diodes).
The invention has a form in which provision is made of a concave mirror for reflecting the light from the group of light emitting elements.
The invention has a form in which the light emitting elements in the group of light emitting elements are arranged in a certain direction and the concave mirror is provided with a cylindrical reflecting surface having a bus line in that direction.
The invention has a form in which the light emitting elements in the group of light emitting elements are arranged in a certain direction, and the concave mirror has a group of concave reflecting surfaces having a plurality of concave reflecting surfaces corresponding to one or more light emitting elements in the group of light emitting elements which are arranged along that direction.
The invention also has a form in which the concave mirror has a focus and the light emitting elements are placed at positions deviating from the focus and whereat rays of light from the light emitting elements are reflected by the concave mirror and become parallel rays of light.
The invention also has a form in which two concave mirrors are provided in a direction orthogonal to the direction in which the light emitting elements are arranged and a part of the rays of light from the light emitting elements is converted into parallel rays of light by one of the concave mirrors and is directed in a first direction, and another part of the rays of light from the light emitting elements is converted into parallel rays of light by the other concave mirror and is directed in a second direction differing from the first direction.
The invention also has a form in which the group of light emitting elements has a plurality of sets of light emitting portions which are provided with a light emitting element emitting red light, a light emitting element emitting green light and a light emitting element emitting blue light.
The invention also has a form in which the group of light emitting elements are provided correspondingly to the plurality of sides of the plate-like member.
The invention also has a form in which the group of light emitting elements are mounted on a side of the plate-like member.
The invention also has a form in which a scattering surface is formed on or near the surface of the plate-like member and the scattering surface shines.
The invention also has a form in which a scattering surface is formed on the bottom surface of the plate-like member.
The invention also has a form in which the scattering surface is designed such that the degree of scattering becomes greater away from the group of light emitting elements.
The invention also has a form in which the scattering surface has a number of cylindrical or pillar-like scattering portions and the height of the scattering portions becomes greater away from the group of light emitting elements.
The invention also has a form in which the scattering surface has a number of grating-like scattering portions and the area of the scattering portions becomes larger away from the group of light emitting elements.
The optical apparatus of the present invention is characterized in that it uses the light source device of the present invention or the light source device having any of the above-described forms to illuminate an object.
The invention also has a form in which the object to be illuminated is film and the image of the film illuminated is read.
The invention also has a form in which the object to be illuminated is a liquid crystal panel and the liquid crystal panel modulates illuminating light to form an image.